Embodiments of the disclosed technology relate to a pixel unit, a liquid crystal display device, and a method for fabricating the same.
In the field of thin film transistor liquid crystal display (TFT-LCD) devices, the aperture ratio of a pixel unit is an important product index. The aperture ratio refers to a ratio of the area of a portion through which light can pass through in each of the pixel units exclusive of the wiring section and the transistor section (generally shielded by a black matrix) to a total area of each of the pixel units. If the pixel units have an increased aperture ratio, the light transmitting efficiency can be increased correspondingly. Therefore, the pixel unit with a high aperture ratio is important in terms of increasing resolution and luminance of the liquid crystal panel and decreasing power consumption thereof.
FIG. 1 is a cross-sectional diagram showing a configuration of a pixel unit in the prior art. As shown in the cross-sectional diagram, the pixel unit comprises an first substrate 101, a common electrode 102, a gate electrode (not shown), an insulating layer 104, a data line 105, a passivation layer 106, a pixel electrode 107, an orientation film 114, a liquid crystal layer 108, a green (G) color filter 111, a red (R) color filter 112 (and a green color filter which is not shown), a light-shielding film 110 and a second substrate 113 laminated in this order from top to down. During fabricating the pixel units, since an inclined angle phenomenon (as identified by an arrow R in the drawing) occurs above the data line of the pixel unit, in the black state of the pixel unit in display, liquid crystal molecules of the liquid crystal layer in a region on both sides of the data line 105 may deflect from a direction perpendicular to the array substrate, resulting in light leakage in this portion of the liquid crystal layer and thus affecting the contrast adversely. For purpose of shielding the light leaking from the region, generally, the width of the light-shielding film 110 above the data line 105 is increased so as to decrease the disadvantageous effect on the liquid crystal panel due to the light leakage from the liquid crystal layer.
However, the increase of the width of the light-shielding film 110 above the data line 105 results in decreasing of the aperture ratio of the pixel unit. For example, for one display panel with a size of 32 inches, if the light-shielding film 110 in the pixel unit is increased by 1 μm, then the aperture ratio of the pixel unit is decreased by 1%, and the transmittance rate of the liquid crystal panel is decreased significantly. Therefore, light leakage from the liquid crystal layer 106 suppresses increasing of the aperture ratio of the pixel unit.